In various mobile radio networks (GSM, CDMA 3G, TETRA or others) groups call connections between more than two subscribers are known, in which traffic channels exist between at least one speaker and at least one listener. Examples of group call connections are the Voice Group Call Service (VGCS) according to 3GPP-TS-42.068 (according to which specification there is provision for speaking, listening, speaking and listening subscribers as well as dispatchers (able to speak without voice authorization tokens)) corresponding essentially to a special conference mode and the Voice Broadcast Service (VBS) according to 3GPP-TS42.069 (according to which voice data of a speaker is transmitted to a plurality of listeners in a predefined area (Voice Broadcast Call Area)) corresponding to a broadcast via one or a plurality of cells and/or to predefined subscribers receiving the VBS.